PARAMETRIC STUDY, MODELING, AND NUMERICAL SOLUTION OF AN INCLINED SOLAR STILL

Abstract

This work numerically studies the heat transfer and fluid flow of an inclined solar still cavity. These devices convert saline or low-quality water into potable transporting water vapor from a warmer surface to a cooler one. The phenomenon of double-diffusion natural convection is considered. The solar still cavity has top and bottom sides inclined and subjected to temperature and concentration gradients, while the vertical walls are adiabatic. Water vapor is considered to be at the saturated state. The governing equations are conservation of mass, energy, momentum, and concentration. The conservation equations are coupled, and their solutions are based on the semi-implicit method for pressure-linked equations (SIMPLE) algorithm. Velocity, temperature, and concentration fields are obtained for a Rayleigh number range in which laminar flow prevails, and for different cavity inclination angles and aspect ratios. The results show that for high Rayleigh numbers an increase in cavity inclination causes the Nusselt and Sherwood numbers and the solar still condensation rate to increase. When the aspect ratio is decreased, the Nusselt and Sherwood numbers also decrease; however, the condensation rate increases due to the increment of the condensable area. A solar still cavity of good thermal performance presented an inclination angle of 45° and an aspect ratio of 1/12 when the thermal Rayleigh number was 106.